Eagle River Timber Bridge

Eagle River Timber Bridge
Other name(s) Eagle River Bridge
Carries Automobiles
Crosses Eagle River
Locale Eagle River, Michigan
ID number 42142021000B050[1]
Material Wood and steel
Total length 152 feet (46 m)[2]
Width 35 feet (11 m)[1]
Height 50 feet (15 m)[2]
Longest span 79 feet (24 m)[lower-alpha 1]
Construction begin 1988
Opened 1990
Daily traffic 849 (in 2007)[1]
Preceded by Lake Shore Drive Bridge

The Eagle River Timber Bridge is a wooden arch bridge that carries highway M-26 over the Eagle River in Eagle River, Michigan. It opened in 1990 as a replacement for the historic Lake Shore Drive Bridge that runs parallel to it.

Contents

History

Construction on the bridge began in 1988.[1][3] The quantity of wood used was equivalent to three or four average-size houses.[2] The bridge opened for highway M-26 traffic in 1990, at which point the neighboring Lake Shore Drive Bridge was restricted to pedestrian use.[4]

On August 26, 1992, the bridge was entered into the 1992 Timber Bridge Design and Construction Award Competition.[5] It was awarded first place in the "Long Span Vehicular Bridges" category.[6]

Design

The bridge is primarily constructed of wood joined together with steel connectors.[2] The bridge is supported by two adjacent arches; one spans 74 feet (23 m) and the other spans 79 feet (24 m).[2] Each arch is constructed from two curved sections joined together by a crown hinge.[2] The road deck is made of wood and covered by an asphalt road surface.[2]

All the timber members were glue-laminated and pressure treated with preservative pentachlorophenol in oil.[2] Any wooden portions which were cut or drilled also had an application of copper naphthenate.[2] The steel pins in the hinges at the crown and abutments were chrome plated to reduce friction and prevent corrosion.[2] All other steel was hot-dipped galvanized, given a tie-coat, and covered by epoxy and a top coat of brown urethane, a system designed to provide thirty years of protection.[2]

Bridge maintenance consists of reapplying preservative to all wooden members and any necessary tightening of bolts.[2]

Notes

  1. ^ One arch spans 74 feet (23 m), the other spans 79 feet (24 m).[2]

References

  1. ^ a b c d Conro, Steve (October 9, 2011). "Eagle River Bridge". BridgeHunter.com: Historic Bridges of the US. http://bridgehunter.com/mi/keweenaw/eagle-river/. Retrieved January 1, 2012. 
  2. ^ a b c d e f g h i j k l m Ness, Brian (June 1991). "The Eagle River Timber Bridge". Mates (54). http://www.michiganhighways.org/indepth/M-26_timberbridge.html. Retrieved January 1, 2012. 
  3. ^ Staff (October 1, 2011) (PDF). Highway Bridge Report (Report). Michigan Department of Transportation. p. 61. http://mi.gov/documents/mdot/MDOT_HighwayBridgeReport_July31-10_CountyB_335026_7.pdf. Retrieved January 1, 2012. 
  4. ^ Staff. "Lake Shore Drive Bridge". State Historic Preservation Office. Michigan State Housing Development Authority. http://www.mcgi.state.mi.us/hso/sites/8218.htm. Retrieved December 31, 2011. 
  5. ^ Bukoski, Glenn (November 1992). "1992 Member Bridge Award Competition". Mates (69). http://www.michiganhighways.org/indepth/M-26_timberbridge.html. Retrieved January 1, 2012. 
  6. ^ "Timber Bridge Design Awards Announce" (PDF). Crossings. Timber Bridge Information Resource Center: p. 2. February 1994. http://www.woodcenter.org/docs/WIT-14-0015.pdf. Retrieved January 2, 2012. 

Further Reading